In one kind of torsion damping device the two coaxial elements together form part of a first part of the device with which a second part of the device is coaxially associated. This second part is itself mounted in facing relationship with the said first part, for rotation within the limits of a predetermined angular displacement and against the action of resilient return means interposed circumferentially between the two said parts. The second of the said parts carries a support, and includes two guide rings which are arranged on either side of the damper plate. The said resilient return means have a stiffness which is greater than that of the resilient centring means.
An arrangement of the above kind is described in, for example, U.S. Pat. No. 4,212,380 and the corresponding French published patent application No. FR 2 386 729A. In that document, an arrangement is proposed in which a friction ring, referred to as a draw ring, is arranged for circumferential sliding movement. The draw ring includes at its inner periphery at least one radially extending tooth means, and is engaged with a circumferential clearance in the corresponding tooth means of the hub. By virtue of this arrangement, the friction torque which is developed between the above mentioned elements of the torsion damping device enables the consequences of any possible bouncing to be suppressed, by providing an accelerated damping of the bouncing movements, while also attenuating the shocks caused by contact of the teeth of the damper plate with the recesses between the teeth of the hub and vice versa.
In practical terms, the draw ring is subjected to the action of a first resilient gripping means, which takes the form of a calibrated resilient gripping ring which bears against a friction ring inserted axially between the damper plate and one of the guide rings. The said resilient gripping ring bears on the other guide ring so as to bias a thrust ring, which is for convenience referred to as a contact ring, towards the damper plate, and the draw ring is gripped between the contact ring and the damper plate. In order to produce a good vibration damping effect, the said draw ring is arranged to exert its forces before the damper plate has become fully meshed with the hub for rotation with the latter.
Even so, a difficulty remains in that the calibration of the resilient ring is not necessarily well adapted to the action of the draw ring, since the gripping effect can be too severe.